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Genetics Block1-12
| Question | Answer |
|---|---|
| In many human tumor cells, abnormal activation of the _________ gene seem to bestow the capacity to divide indefinitely | telomerase |
| specialized elements that ensure the accurate duplication and segregation of chromosomes include telomeres, origins of replication, and ____________ | centromeres |
| the components of eukaryotic chromosomes include DNA, _____, and nonhistone proteins | histones |
| ______ is the generic term for any complex of DNA and protein found in a cell's nucleus | Chromatin |
| The most rumidentary DNA packaging unit which involves four types of histones is the ________. | nucleosome |
| the largest class of nonhistone proteins foster or regulate ________ and RNA processing during gene expression. | transcription |
| packaging into nucleosome condenses naked DNA about ______ | 7-fold |
| tow small acrocentric chromosomes in the great apes fused to form ______ chromosome 2 in humans | metacentric |
| The duplication of chromoosmal DNA depends on origins of replication and ________ | telomeres |
| In a typical human cell, DNA polymerase replicates about _______ nucleotides per second. | 50 |
| the DNA running both ways from one origin of replication to the endopoints where it merges with DNA from adjoining replication forks is called a replication unit, or _________ | replicon |
| the telomeres of all mammals and most of the other higher animals contain the same repetitive DNA sequence. The bases in the sequence are | TTAGGG |
| Even though telomeres normally carry no genes, they contain essential information for the duplication, segregation, and stability of __________ | chromosomes |
| the _______ of eukaryotic chromosomes assure their precise distribution during cells division | centromeres |
| Centromeres are contained within blocks of repetitive, simple noncoding sequences known as _______ DNAs | satellite |
| The _____ is the specialized structure composed of DNA and proteins that is the site at which chromosomes attach to the spindle fibers. | kinetochore |
| cells express their genes mainly during ______ when the chromosomes have decondensed, or decompacted | interphase |
| when viewed unde the light microscope, certain regions of chromosomes that have been stained with certain DNA-binding chemicals appear lighter than others. These regions are called ________ | euchromatin |
| chromosomal regions that remain condensed in heterochromatin at at most times in all cells are known as ________ heterochromatin | constitutive |
| regions of chromosomes that are heterochromatic in some cells and euchromatic in other cells of the same organism are known as _________ heterochromatin. | facultative |
| inactive X chromosomes that appear in interphase cells as darkly stained heterochromatin masses are called ________ | Barr bodies |
| Drosophila salivary gland contain giand chromosomes called ______ chromosomes consisting of many identical chromatids lying in parallel register. | polytene |
| the centomeres of polytene chromosomes fuse to form a dense heterochromatic mass known as the ________ | chromocneter |
| when observing the interphase nucleus of a eukaryotic cell, a certain large sphere-shaped structure may be seen clearly. This structure is called the ________. | nucleolus |
| the enzyme that some organisms use to replicate DNA at the 5' ends of chromosomes is called | telomerase |
| what is NOT usually seen when a cell loses telomemrase activity? | many normal somatic cells gain the ability to divide indefinitely. |
| the chromosome can be considered a dynamic organelle for ______, ______, ______, ________ of DNA | expression, segregation, replication, packaging |
| the components of a chromosome include one long DNA molecule and ______ | proteins |
| by weight, chromatin consists roughly of 1/3 DNA, 1/3 _______, 1/3 _______. | histones, nonhistones |
| histones and DNA have a strong attraction for each other because | DNA is negatively charged and histones are positively charged |
| what are the roles of nonhistone proteins found in chromatin? | structural, replication, chromosome segregation |
| The nonhistone proteins in chromatin have functions that | such as tissue-specific transcription fators, activity at different moments in the life cycle, centromere function actitivity |
| the first level of compaction of DNA concsists of | DNA winding around histones to form small nucleosomes |
| nucleosomal chromatin with a diameter of 100A supercoils into a 300A superhelix. The histone that appears to be responsible for this compaction is | H1 |
| in DNA, the 300A fiber is formed into structural loops. Responsibility for this function appears to lie with: | certain nonhistone proteins |
| at what stage of mitosis do we first see a chromosome that is compacted 250-fold over the 400fold compacted 300A fiber? | metaphase |
| which of teh following is not a piece of evidence that supports the radial loop-scaffold model of DNA packaging | Toposimerase II assists in 100A packaging |
| the total compaction of DNA as seen in metaphase chromosomes is approximately ____ fold | 10000 |
| At low resolution we can see about _____ bands while at high-resolution we see about _______ bands. | 300, 2000 |
| chromosome banding patterns can be used for | analyse chromosomal differences between species, locate genes, reveal the cause of certain genetic diseases |
| with regard to the typical human cell, there are _______ origins of replication that function simultaneously. | multiple |
| in mammalian cells, replication proceeds | bidirectionally |
Created by:
hiroko2013